The present invention relates to a gas control device integrated on a panel and provided in a high purity gas supply system for manufacturing a semiconductor device, so that the gas is cleaned and the supply thereof is controlled.
A conventional gas control device provided in the high purity gas supply system for manufacturing a semiconductor device comprises a plurality of independent gas control units connected by joints and pipelines, thereby to form a gas control line. The gas lines are disposed in parallel on a base plate so as to be integrated on a panel.
However, when a number of independent gas control units are connected by the pipelines and joints, the gas line becomes long and the inner capacity of the gas control device within the semiconductor manufacturing system becomes large. In addition, since each gas line has different passage structure, the gas control unit cannot be easily attached or detached. Hence the total manufacturing lead time for designing, producing and assembling the manufacturing system is increased. As a result, the initial rise time at the time of installment of the system becomes longer, and the manufacturing processes become complicated and therefore expensive. In addition, since it is difficult to replace the gas control units, the conventional device cannot deal with a situation where the flow passages must be changed.
Regarding the performance of the gas control device, there are generated welding fumes and particles which deteriorate the welded parts and hence shorten the life of the pipeline. With regard to the cost, the yield of the products is low and the cost for maintenance is high. In addition, since the gas control device cannot be reduced in size, when integrating the device on the panel, there occurs cases where the gas lines are disposed in upper and lower surfaces of the panel or in multiple layers.
In order to connect the gas control units in the gas line to a passage block, there has generally been employed the use of a flange or bolts. However, such a connecting method causes unbalance in tightening force of each bolt, thereby decreasing reliability, and moreover, the assemblage man-hour is increased, so that the cost rises.
In order to resolve these problems, the applicant of the present invention has proposed in Japanese Patent Application Laid Open 10-300000, a structure for integrating the gas control units on a panel wherein the gas control units are mounted on a base plate and connected to each other by a plurality of gas passage blocks. Such a structure will be schematically described with reference to FIG. 10.
Referring to FIG. 10, a passage block 101 has a gas inlet passage 102 and a gas outlet passage 103 formed therein. Peripheral sealing beads 104 and 105 are formed at the openings of the passages 102 and 103. An annular metal gasket 106 is disposed between the sealing bead 104 of the passage block 101 and the sealing bead 105 of the adjacent passage block 101. An external thread 107 is formed on each passage block 101 on the outer periphery thereof adjacent one end portion, and a nut 108 is engaged with the thread 107. A union nut 109 mounted on the nut 108 engages an external thread 110 formed on the outer periphery of the adjoining passage block 101 at the end portion thereof. Thus the adjacent passage blocks 101 are hermetically detachably connected to each other while communicating the gas outlet passage 103 of one block with the gas inlet passage 102 of the other block. The connected passage blocks 101, only two of which are shown in FIG. 10, are detachably mounted on a base plate 111.
Desired gas control units such as manual diaphragm valve 112 having a toggle joint and a filter unit 113 are mounted on the passage blocks 101. The diaphragm valve 112 and the filter unit 113 each has a connecting member 114 which is inserted in an upper opening 115 formed in each passage block 101 interposing a metal gasket 116. Thus a gas inlet passage 117 formed in the connecting member 114 is communicated with the gas inlet passage 102 and a gas outlet passage 118 formed in the connecting portion 114 is communicated with the gas outlet passage 103 through the gasket 116. A union nut 119 disposed on the outer periphery of the connecting member 114 is screwed on an external thread 120 formed on the outer periphery of an upper portion of the passage block 101. Thus the connecting member 114 is hermetically detachably mounted on the passage block 101. Besides the manual diaphragm valve 112 and filter unit 113, other gas control units such as an automatic diaphragm valve, mass flow controller, regulator, automatic diaphragm valve having a check valve may be selectively used.
The above-described conventional integrated gas control device is advantageous in that while the passage blocks 101 are horizontally connected to one another by way of the end portions thereof, the gas control units 112 and 113 are vertically disposed and connected to the passage blocks 101. Accordingly the gas passage structure and gas lines can be linearly disposed and the size thereof reduced, resulting in decrease in the overall size of the device.
Since the gas line can be constructed utilizing standardized parts, the passage can be largely arbitrarily constructed. Accordingly not only the total manufacturing lead time for designing, producing and assembling the manufacturing device and the initial rise time are decreased, but the arrangement of the passages can be changed with more ease when required. In addition, since the pipeline need not be welded for connecting the passage blocks 101, the fumes can be prevented from generating, so that it is possible to elongate the life of the device and to improve the yield of the products. Moreover, the gas control units 112 and 113 can be easily detached from the passage blocks 101 by simply removing the union nuts 119 on the connecting members 114, and hence easily replaced. Therefore, the maintenance of the device is simplified and the cost thereof decreased.
The union nut 119 is used in order to attach the control unit 112 or 113 to the passage block 101, so that the entire control unit can be fastened with a well-balanced force without applying couple of forces thereto. Hence a tight seal can be maintained, thereby improving reliability.
In the conventional integrated gas control device, since the adjacent passage blocks are connected to each other by way of screws, it is necessary to interpose the metal gasket 106 between the sealing beads 104 and 105 at the end portions of the passage blocks 101 so that the seal may be ensured. However, since the number of sealing portions is increased, there is a possibility of deteriorating the overall sealing effect. In order to prevent such a problem from occurring, the metal gasket 106 and sealing beads 104 and 105 must be accurately machined. Moreover, the threads 107 and 110 must be formed on the outer periphery of the passage block 101 and the nut 108 and the union 109 must be provided, resulting in the increase in machining portions and the number of parts. Accordingly, the lead time for the manufacturing the device is increased, and the manufacturing process becomes complicated so that the cost is increased. Furthermore, since a space for moving the union nut 109 engaged with the thread 110 is necessary, a sufficient space is still required between each of the gas control units 112 and 113 mounted on the passage blocks 101, thereby rendering it impossible to sufficiently shorten the gas line.